hrtimer: fix recursion deadlock by re-introducing the softirq
Impact: fix rare runtime deadlock
There are a few sites that do:
spin_lock_irq(&foo)
hrtimer_start(&bar)
__run_hrtimer(&bar)
func()
spin_lock(&foo)
which obviously deadlocks. In order to avoid this, never call __run_hrtimer()
from hrtimer_start*() context, but instead defer this to softirq context.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 0702c4d..2062833 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -253,7 +253,8 @@
BLOCK_SOFTIRQ,
TASKLET_SOFTIRQ,
SCHED_SOFTIRQ,
- RCU_SOFTIRQ, /* Preferable RCU should always be the last softirq */
+ HRTIMER_SOFTIRQ,
+ RCU_SOFTIRQ, /* Preferable RCU should always be the last softirq */
NR_SOFTIRQS
};